Hybrid vehicles potentially offer fuel efficiency and vehicle driving range improvements over non-hybrid vehicles. One example of a hybrid vehicle includes an engine that may be selectively coupled to an electrical machine and a transmission according to vehicle operating conditions. The engine may be selectively coupled to the electric machine and transmission via an electrically or hydraulically actuated driveline disconnect clutch. The driveline disconnect clutch allows the electric machine to provide torque to vehicle wheels during low torque demand conditions without having to operate the engine and without having to supply torque to rotate an engine that is not combusting an air-fuel mixture. The driveline disconnect clutch may also be used to restart the engine from a condition of no rotation via the electric machine.
The driveline may also include a dual mass flywheel positioned between the engine and electric machine to reduce driveline compliance issues. However, the dual mass flywheel may flex and oscillate under some conditions, and the oscillations may be apparent and objectionable to a driver. In some examples, dual mass flywheel oscillations may be induced via closing the driveline disconnect clutch.
The inventors herein have recognized the above-mentioned disadvantages and have developed a method of adjusting operation of a hybrid vehicle driveline, comprising: adjusting an actuator in response to a speed or torque differential across a dual mass flywheel (DMF) positioned in the hybrid vehicle driveline between an engine and a driveline disconnect clutch where the DMF is driveline component positioned in between the engine and the driveline disconnect clutch.
By adjusting an actuator in response to a condition of a DMF, it may be possible to reduce torque disturbances in a driveline of a hybrid vehicle. For example, if the speed differential across the DMF is increasing, springs within the DMF may be compressing and torque of a driveline integrated starter/generator (DISG) may be adjusted to reduce compression of the DMF springs.
The present description may provide several advantages. Specifically, the approach may reduce driveline torque disturbances of a hybrid driveline. Further, the approach may improve vehicle drivability. Further still, the approach may reduce driveline wear, thereby increasing the operating life of the driveline.
The above advantages and other advantages, and features of the present description will be readily apparent from the following Detailed Description when taken alone or in connection with the accompanying drawings.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.